diff --git a/Core/ELF/PrxDecrypter.cpp b/Core/ELF/PrxDecrypter.cpp
index cf0e980e37..a3b8fe46c4 100644
--- a/Core/ELF/PrxDecrypter.cpp
+++ b/Core/ELF/PrxDecrypter.cpp
@@ -2,11 +2,8 @@
 #include <array>
 #include <string.h>
 
-extern "C"
-{
 #include "ext/libkirk/kirk_engine.h"
 #include "ext/libkirk/SHA1.h"
-}
 #include "Common/Common.h"
 #include "Common/Log.h"
 #include "Common/Swap.h"
diff --git a/Core/FileSystems/BlockDevices.cpp b/Core/FileSystems/BlockDevices.cpp
index e6eb46554a..d74639a56c 100644
--- a/Core/FileSystems/BlockDevices.cpp
+++ b/Core/FileSystems/BlockDevices.cpp
@@ -35,12 +35,9 @@
 #include "Core/Util/PathUtil.h"
 #include "libchdr/chd.h"
 
-extern "C"
-{
 #include "zlib.h"
 #include "ext/libkirk/amctrl.h"
 #include "ext/libkirk/kirk_engine.h"
-};
 
 static u16 ReadLE16(const u8 *ptr) {
 	return ptr[0] | (ptr[1] << 8);
diff --git a/Core/HLE/sceIo.cpp b/Core/HLE/sceIo.cpp
index 293b388ca0..bb275b111a 100644
--- a/Core/HLE/sceIo.cpp
+++ b/Core/HLE/sceIo.cpp
@@ -58,9 +58,7 @@
 #include "Core/FileSystems/ISOFileSystem.h"
 #include "Core/FileSystems/DirectoryFileSystem.h"
 
-extern "C" {
 #include "ext/libkirk/amctrl.h"
-};
 
 #include "Core/HLE/sceIo.h"
 #include "Core/HLE/sceRtc.h"
diff --git a/Core/HLE/sceKernelSemaphore.h b/Core/HLE/sceKernelSemaphore.h
index 74002ff9d6..410fbe2f17 100644
--- a/Core/HLE/sceKernelSemaphore.h
+++ b/Core/HLE/sceKernelSemaphore.h
@@ -80,7 +80,4 @@ void __KernelSemaInit();
 void __KernelSemaDoState(PointerWrap &p);
 KernelObject *__KernelSemaphoreObject();
 
-extern "C"
-{
 #include "ext/libkirk/kirk_engine.h"
-}
diff --git a/Core/HLE/scePspNpDrm_user.cpp b/Core/HLE/scePspNpDrm_user.cpp
index 37c35b9386..6ef44d4ebf 100644
--- a/Core/HLE/scePspNpDrm_user.cpp
+++ b/Core/HLE/scePspNpDrm_user.cpp
@@ -1,10 +1,5 @@
-// kirk_engine.h includes AES.h from outside its own extern "C" block, so whoever pulls it in first
-// decides the linkage the AES_* functions get. Do it here, the way PrxDecrypter.cpp does, or they
-// come through sceChnnlsv.h below with C++ linkage and fail to link.
-extern "C" {
-#include "ext/libkirk/kirk_engine.h"
+#include "ext/libkirk/AES.h"
 #include "ext/libkirk/amctrl.h"
-}
 
 #include "Core/HLE/scePspNpDrm_user.h"
 #include "Core/MemMapHelpers.h"
diff --git a/Core/Util/PSARUnpack.cpp b/Core/Util/PSARUnpack.cpp
index e7aff71097..a0880bc6fa 100644
--- a/Core/Util/PSARUnpack.cpp
+++ b/Core/Util/PSARUnpack.cpp
@@ -37,9 +37,7 @@
 #include "Core/System.h"
 #include "Core/Util/PSARUnpack.h"
 
-extern "C" {
 #include "ext/libkirk/kirk_engine.h"
-}
 
 // A PSAR record is [header][entry], where the header is 0x150 bytes of PRX-style encryption
 // metadata and the entry is 0x110 bytes describing one file. Pre-decrypted archives (rare, and
diff --git a/Core/Util/PkgUnpack.cpp b/Core/Util/PkgUnpack.cpp
index 105d52f4e6..48d03a9a66 100644
--- a/Core/Util/PkgUnpack.cpp
+++ b/Core/Util/PkgUnpack.cpp
@@ -31,9 +31,7 @@
 #include "Core/System.h"
 #include "Core/Util/PkgUnpack.h"
 
-extern "C" {
 #include "ext/libkirk/AES.h"
-}
 
 // See docs/pkg_notes.md. Field offsets in the 0xC0-byte header:
 static const u32 PKG_MAGIC = 0x7F504B47;  // "\x7FPKG"
diff --git a/ext/libkirk/AES.h b/ext/libkirk/AES.h
index ee61f46490..08e2260c99 100644
--- a/ext/libkirk/AES.h
+++ b/ext/libkirk/AES.h
@@ -3,6 +3,10 @@
 
 #include "kirk_common.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 #define AES_KEY_LEN_128	(128)
 #define AES_KEY_LEN_192	(192)
 #define AES_KEY_LEN_256	(256)
@@ -48,4 +52,8 @@ int	rijndaelKeySetupEnc(u32 [], const u8 [], int);
 int	rijndaelKeySetupDec(u32 [], const u8 [], int);
 void rijndaelEncrypt(const u32 [], int, const u8 pt[16], u8 ct[16]);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* __RIJNDAEL_H */
diff --git a/ext/libkirk/SHA1.h b/ext/libkirk/SHA1.h
index 43493e3319..2735c3faf2 100644
--- a/ext/libkirk/SHA1.h
+++ b/ext/libkirk/SHA1.h
@@ -2,6 +2,10 @@
 
 #include "kirk_common.h"
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /* POINTER defines a generic pointer type */
 typedef unsigned char *POINTER;
 typedef const unsigned char *CONST_POINTER;
@@ -34,3 +38,7 @@ void SHAUpdate(SHA_CTX *, const BYTE *buffer, int count);
 void SHAFinal(BYTE *output, SHA_CTX *);
 
 void endianTest(int *endianness);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/ext/libkirk/kirk_engine.h b/ext/libkirk/kirk_engine.h
index de90c4d48e..153e8c0b34 100644
--- a/ext/libkirk/kirk_engine.h
+++ b/ext/libkirk/kirk_engine.h
@@ -26,6 +26,11 @@
 
 #pragma once
 
+// kirk4()/kirk7() below take a size_t, and nothing here provided it - the header only ever
+// compiled because whatever included it had pulled in a definition first. Core/HLE/scePspNpDrm_user.cpp
+// includes libkirk before anything else, so it doesn't.
+#include <stddef.h>
+
 #include "kirk_common.h"
 #include "SHA1.h"
 #include "AES.h"